Although Carroll himself admits that horror film audiences are attracted primarily by the narrative elements of the films they consume, and not by the slimy, distasteful monster that in fact is the defining feature of the genre, he still emphasizes that a film must depict the behavior of at least one monster to provoke horror. Besides, the monster must be perceived by audiences in the film to be monstrous or abnormal, i.e. to be supernatural.
First of all, I am going to discuss about Carroll's account of the monster and its role in horror films. In Carroll's point of view, to provoke fear, one must be threatening; to provoke a sense of disgust, one must be impure. As horror is made up of fear and disgust, one must be both threatening and impure to provoke horror. Therefore, only a monster can do so.
To the point of being impure, Carroll elaborate in this way.
Being an impure figure, a monster has to be interstitial, contradictory, incomplete, or formless. An interstitial monster is the monster that conflates categories that are held to separate, such as inside/outside, living/dead, insect/human, flesh/machine, etc. typical example for an interstitial monster is a werewolf. It is sometimes human and sometimes animals, but never exactly a human or an animal. What is incomplete and formless are usually indicated by flesh, meat, blood, dirt, etc. in a horror film. All these features are used to generate a sense of disgust among audience in the theatre.
Is a monster the only one to be threatening and impure? Definitely not. Among many typical horror films, we can find other horror themes that can generate fear and disgust successfully. For instants, insects and wild animals are common topic for horror film. The horror from spiders, rats, shark,